Further studies on the localization of catalase in peripheral blood neutrophils using the sucrose gradient centrifugation procedure will be attempted. The separation of cytoplasmic granules will allow a more precise definition of these granules. The plan is to identify catalase and other associated enzymes with reference to the granules since the former enzyme is believed to be localizable in granules which appear to be identical to primary or azurophil granules. Isoelectric focusing method in conjunction with diaminobenzidine (DAB) reaction at pH 9.0 will be employed to identify and characterize peroxidatic catalase of leukocytes and their granules. The patterns will be examined in mixed leukocytes of human peripheral blood in health and disease. BIBLIOGRAPHIC REFERENCE: Nishimura, E.T., Whest, G. M. and Yang, H. Y. Cytochemical Localization of Peroxidatic Catalase in Human Leukocytes. Lab. Invest. 34:60. 1976.